Variable pitch impeller



' Oct. 5; 1948. c. w. CLINE 2,450,420

VARIABLE PITCH IMPELLER Filed Sept. 15, 1946 3 Sheets-Sheet 1 Fig.

75 INVENTOR. 79 73% "-74 M72 G/PA/VMORE m GLl/VE v 1T] BY I \/7 88ATTORNEY Oct. 5, 1948. c. w. CLINE I 2,450,420

-VARIABLE PITCH IMPELLER Filed Sept. 13, 1946 3 Sheets-Sheet 2 wINVENTOR.

GRAN/"ORE W ULl/VE ATTORNEY Oct. 5, 1948. c. w. CLINE VARIABLE PITCHIMPELLER 3 Sheets-Sheet 3 Filed Sept. 15, 1946 Fig.5

' FLY MM W M m M. m

A T TORNE Y Patented Oct. 5, 1948 UNITED STATES PATENT OFFICE VARIABLEPITCH IMPELLER Cranmore W. Cline, United States Navy,

Jacksonville, Fla.

(Granted under the act of March 3, 1883, as amended April 30, 1928; 3700. G. 757) 2 Claims.

This invention relates to variable pitch impellers and more particularlyto mechanisms for adjusting the pitch of the same.

An object of the invention is to provide an improved impeller of simpleconstruction and adapted to have its pitch adjusted while in operation.

Other objects of the invention are to provide an improved variable pitchimpeller for driving the reel of an aircraft tow target at differentrates of speed; to provide an improved impeller, of the characterdescribed, having actuating means operable by the rotation of theimpeller; to provide an improved mechanism for adjusting the pitch of animpeller during rotation of the same; to provide a control for themanual operation of the pitch of the blades on the impeller; to providea control for utilizing, at the will of the operator, the impeller driveshaft as a source of power for the changing of the pitch of the impellerblades, in such a direction that will cause the impeller to stoprotating; to provide an improved impeller mechanism, of the characterdescribed, wherein the control means has connection with the impellerblades and with the drive shaft of said impeller and includes means forutilizing the rotation of said drive shaft to impart oscillation to saidblades about their respective axes so as to vary the pitch of the same;and to provide improved elements and arrangements thereof in an impellermechanism of the character described and for the purpose set forth.

In accomplishing these and other objects of the present invention, Ihave provided improved details of structure, the preferred form of whichis illustrated in the accompanying drawings, wherein:

Fig. 1 is a transverse, vertical, sectional View of a portion of anaircraft fuselage having an impeller and control mechanism embodying thefeatures of the present invention mounted thereon and therein and shownconnected to a tow target reel. I

Fig. 2 is a longitudinal, sectional view of the impeller.

Fig. 3 is a cross-sectional view, taken on the line 33 of Fig. 2.

Fig. 4 is an isometric view of a portion of the traversing mechanism,showing its relation to the drive shaft of the impeller.

Fig. 5 is a cross-sectional view, taken on the line 5-5 of Fig. 2,showing the connection between the impeller and the flexible cable whichextends to the control mechanism.

Fig. 6 is a detailed sectional view of the control mechanism, taken onthe line 6-6 of Fig. 1.

Fig. 7 is a cross-sectional view of the control mechanism, taken on theline 'l! of Fig. 6.

Referring more in detail to the drawings:

In Fig. 1, the numeral I0 designates a portion of the fuselage of anaircraft, such as an airplane, having an impeller l I mounted thereonfor driving a tow target reel l2, or other means, which is mounted in asuitable frame 13. A driven shaft l4, coupling l5, and gear box l6operatively connect the impeller H to the reel l2, the gear boxpermitting selective engagement and disengagement of said reel relativeto the shaft and its coupling. As will be hereinafter more fullyexplained, the pitch of the impeller is adapted to be varied by acontrol mechanism I! which is operatively connected to the gear box IEby a flexible drive shaft or cable l8 and to said impeller by a secondflexible drive shaft or cable l9. e

The impeller ll includes an upright mounting support or standard 20 uponwhich a cylindrical nacelle or shell 2i (Fig. 2) is mounted in sub--stantially parallel relation to the fuselage (Fig. 1).

As shown in Fig. 2, a cylindrical bearing housing or collar 22 isdisposed concentrically within the forward portion of the shell 2! andhas an external, radial flange 23 adjacent its forward end, which flangeoverlies the forward open end of said shell and is secured thereto bysuitable stud bolts 24 and nuts 25. The innermost end of the bearinghousing 22 is of reduced diameter and is provided with an internal,radial flange 26 to form an annular recess or socket 21 for receiving aball bearing assembly 28. An axial drive shaft 29, having the bearingassembly 28 confined upon the inner end portion thereof, extends throughthe bearing housing 22 and projects forwardly thereof. The rearextremity of the shaft 29 carries a bevelled pinion 30 which has itsteeth in constant mesh with the teeth of a complementary pinion 3|mounted on the upper end of the driven shaft M, the latter extendinginto the shell 2i and being journalled therein by a ball bearingassembly 32.

A hub 33, having an axial bore 34, is keyed or" radial sockets 36 (Fig.3) which are preferably equally-spaced and have been illustrated asbeing four in number.

Each socket 36 is adapted to receive the shank or root of a blade 31 andis progressively enlarged or stepped outwardly to provide a plurality ofcounterbored or shouldered portions. Each blade 3? has its shank formedcomplementary to its socket and carries in scquential order a small ballbearing assembly 38, a spur gear 39, Fig. 2, a lock nut 40 and a largeball bearing assembly 4| which engage within the counterbored portionsof said socket. A housing or casing 42 encloses the hub and includes anose or cap section 43 and coacting annular cages or sections 44 and 55,the latter encircling said hub and rotatably confining the blades shankswithin their sockets.

As shown in Figs. 2 and 3, the hub 33 is formed with a plurality oflongitudinal ports or keyways 46 intermediate and extending at rightangles to the sockets 36, with each keyhole communicating with theadjacent counterclockwise socket. A reciprocable bar or rod 41, having agear rack 48 secured thereto, is, slidably mounted in each keyhole 46and projects rearwardly therethrough. The teeth of each gear rack 48 arein constant mesh with the teeth of the adjacent counterclockwise spurgear 39, whereby the blade upon which said gear is mounted is oscillatedabout its axis by reciprocation of the rod 47 carrying said rack. Ineffect, the rods and gear racks form a part of the control mechanism Hand are adapted to be simultaneousl and uniformly reciprocated by meansof an actuating or connecting member 49 which is slidably confined uponthe drive shaft 29 rearwardly of the hub.

As is most clearly shown in Fig. 4, the member 49 includes a radialflange 50 and a plurality of equally-spaced, rearWardly-directed fingerswhich are arcuate in cross-section and snugly engage the peripheralsurface of the shaft 29 (Fig. 2). Keyholes 52 are formed in the flange59 of the connecting member for receiving the-rearward k ends of therods 41 and connecting the same to said member. lJhe fingers 5| extendlongitudinally between radial ribs or lugs 53 formed on the shaft 29 andhave their rearward or free ends reduced in thickness for receiving anannular, splined spacer 54 and a pair of annular nuts or rings 55 whichare screw-threaded upon said fingers ends and confine the spacerthereupon with its splines between said fingers. Due to the relation ofthe fingers and the lugs 53, the member 49 rotates with the drive shaftand is slidable longitudinally thereof. For receiving an annular,rearwardly-directed bearing collar 56 formed on the hub 33 (Fig. 2), theinner, forward portions of the fingers are recessed as shown by thenumeral 51 (Fig. 4).

A ball bearing assembly 58 is mounted within the bearing housing 22,Fig. 2, forwardly of its flange 23 and in surrounding relation to thefingers 5|, for centering the connecting member 49 within said housingand permitting relative rotation and reciprocation of said member. Inorder to reciprocate the connecting member, a pair of annular,traversing elements or guides 59 and 69 are disposed within the rearwardportion of the bearing housing 22 concentrically of the drive shaft 29.The outer or female guide 59 is fixed against rotation within thebearing housing by suitable means, such as splines or keys 6|, and isinternally recessed to receive a ball bearing assembly 62 which isconfined upon the rearward ends of the fingers 5| of the connectingmember.

by the nuts 55. An annular bearing cap 63 connects the female guide tothe bearing assembly 62, whereby reciprocation of said guide is tran$-mitted to the member 49 without interfering with the rotation of saidmember. Forward reciprocation of the member is limited by a spacer ring64 which encircles the fingers of the connecting member forwardly of thebearing assembly 62 and which is adapted to engage the bearing assembly58 upon such reciprocation.

The inner or male guide is screw-threaded within the outer,non-rotatable guide 59 and is rotatably supported by an annular bearingmember 65 which is secured to the bearing housing 22. immediatelyforward of its recess 21. An internal, annular flange portion 66projects rearwardly from the guide 60 and is rotatably confined upon thebearing member 65 b a coacting radial flange or shoulder 61 formedinternally of and at the forward end of said bearing member. Forimparting rotation to the inner guide 60 so as to reciprocate the outerguide 59, the flange portion 66 of said inner guide has a worm gear 68secured externally thereon. A suitable thrust bearing 69 encircles theflange portion and bearing member rearwardly of the worm gear 68.

As is clearly shown in Fig. 5, a worm 70 has its teeth in constant meshwith the teeth of the worm gear 68. The worm 19 is carried by a shortshaft H which is journaled in the bearing housing 22 and extends throughthe wall of the shell 2| into the standard 20 (Fig. 2), being suitablycoupled to the flexible shaft l9. By virtue of the foregoingarrangement, rotation of the flexible shaft I9 is transmitted throughshaft H, worm 10 and worm gear 68 to the inner traversing guide 6|].Since the outer traversing guide 59 is keyed against rotation, rotationof the inner member causes sliding movement of said outer member. Thismovement is imparted through the bearing assembly 62, actuating member49, and rods 4! to the gear racks 48 so as to oscillate the spur gears39 and the blades 31 about their respective axes during rotation of thehub 33 and said blades about the longitudinal axis of the shaft 29.

Rotation of the flexible shaft I9 is affected by means of the controlmechanism l1. As shown in Figs. 1, 6 and 7, the mechanism includes arectangular housing or casing 12 mounted on the frame l3 and having apair of parallel shafts 13 and I4 journaled therein. The flexible shaftsI8 and [9 are connected to the shafts l3 and 14, respectively, whichshafts have drums or rollers 15 and 16 mounted thereon, whereby saidshaft 13 and its roller 15 are constantly driven by said flexible shaftl8. .An idler assembly 11 is disposed Within the casing I2 foroperativel connecting the rollers 15 and I6 and includes aspring-pressed yoke member '18 having its parallel legs or armsextending at right angles to said rollers between the shafts 13 and I4.The yoke member l8 rotatably supports an idler drum or roller 19, bymeans of a suitable shaft 89, which roller is parallel to and adapted tobe engaged with the rollers 15 and 16 upon movement of said yoke memberin a plane transverse to the longitudinal axes of said latter rollers.

A cam element 8| is pivotally supported externally of the casing 12,between suitable lugs or cars 82, in engagement with a pin or button 83carried by the yoke member and extending through an opening in saidcasing, whereby pivoting of the cam element in a counter-clockwisedirection causes inward reciprocation of said yoke member and engagementof its idler roller with the rollers 15 and 16. The button 83 is held inengagement with the cam element 8| by a, coiled spring 84 which isconfined between an annular boss 85 formed internally of the easing anda co-axial pin 86 carried by the yoke member opposite said button.Displacement of the yoke member is prevented by the engagement of thebutton in the casing opening and the action of the pin 85 with theannular boss 85. A U-shaped guide element or bracket 31 is mountedinternally of the casing in engagement with the yoke member forpreventing turning or pivoting of said member about the axes of itsbutton and pin. Upon engagement of the rollers, rotation is imparted tothe roller 16, shaft M, flexible shaft I9, shaft ll, Fig. 5, and worm"l0 so as to drive the worm gear 68 and thereby turn the blades 31 abouttheir respective axes, as explained hereinbefore. It is pointed out thatone end of the shaft l4 ext-ends entirely through the casing and has ahand wheel 88, Fig. 6, mounted on it projecting end to permit manualoscillation of the blades and adjusting of the pitch thereof.

Operation The operation of a variable pitch impeller and controlmechanism therefor, constructed as described, is as follows:

During take-offs and landings, the blades 3? of the impeller are fullfeathered to offer as little wind resistance as possible. The featheringof the blades is accomplished manually, by means of the hand wheel 88upon take-oifs and either manually or mechanically by pivoting the camelement 8 i upon landings.

When it is desired to rewind the tow target reel 12, the driven shaft I4is operatively connected to said reel by manipulation of the gear boxIt. Since the shaft i4 is driven by its connection with the drive shaft29, rotation of the impeller blades and their hub 33 is transmitted tothe reel. Although rapid rewind is desirable, it is essential to controlthe speed of rotation of the impeller to prevent overspeeding of thesame. The load imposed on the impeller is constantly reduced by reelingin of the cable with the result that the speed of said impeller isincreased. By increasing the pitch of the impeller blades, therotational speed of the same is decreased and the rate of rewindreduced. This control is important during completion of the rewind andpermits inching in of a target sleeve (not shown).

In order to feather or decrease the pitch of the impeller blades, thecam element is! is swung in a counter-clockwise direction so as to movethe idler assembly i1 inwardly or to the right (Figs. 6 and '7) and moveits roller i9 into engagement with the rollers 15 and i6. Since theroller i is rotated by the connection of its shaft 13 to the flexibleshaft 18, in turn driven by its connection with the gear box it, theroller l8 and its shaft 14 are rotated by the aforesaid engagement ofthe rollers. This rotation is imparted to the inner traversing member 68through the flexible shaft l 9, shaft 1 i, worm if! and worm gear 68(Figs. 2 and 5).

Due to the provision of the keys BI and the screw-threaded connectionbetween the traversing guides, the outer traversing guide 59 is slidoutwardly longitudinally of the shaft 29 by rotation of the guide BE.The bearing assembly 62 and cap 63 impart similar longitudinal movementto the actuating member at so as to reciprocate the rods 4? and theirgear racks 48 forwardly, thereby turning the spur gears 39 and theblades 31, upon which said gears are mounted, about their respectiveaxes. In this manner, the

- departing from the spirit of the invention.

6 pitch of the blades is increased so as to decrease the rotationalspeed of the same and thereby reduce the rate of rewind of the reel l2.

Full feathering of the blades is accomplished by continued actuation ofthe control mechanism H which moves the racks l8, rods ll, member 49,bearing assembly 62, cap 63 and guide 59 outwardly until the spacer ring64 engages the bearing assembly 58. It is pointed out that actuation ofthe control mechanism continues so long as the cam element 8i maintainsthe idler assembly 17 inwardly of the casing l2 with its roller 19 inengagement with the roller '15 and 76. Upon release of the cam element,the compression of the spring 84 urges the assembly outwardly or to theleft (Figs. 6 and 7) so as to disengage the rollers and thereby renderthe control mechanism inoperative. Due to the construction of theimpeller, the blades thereof will retain the pitch to which the samehave been adjusted at the moment of disengagement of the rollers andnonoperation of the control mechanism.

As has been explained, the pitch of the impeller blades may be variedmanually, at will, by the provision of the direct connected shaft l9between the operator and the pitch changing mechanism, manuallycontrolled by the hand wheel 88. Of the three rubber covered rollers inthe control box, two of these rollers are respectively connected to theflexible shafts. One of the drive shafts goes to the pitch changingdevice and the other one goes to the impeller main power drive shaft.The third and last rubber covered roller is merely an idler and is thereto provide a means of coupling, at will, the two other before mentionedrollers. When the two rollers that are connected to the flexible driveshafts are coupled together, by means of the idler roller, the followingresult is obtained. The roller that is driven by the impeller main driveshaft turns the idler roller, and this idler roller in turn, turns theroller on the pitch control drive shaft in a direction which tends tostop the rotation of the impeller. This result may be accomplished withor without a load on the impeller main drive shaft. If there is no loadon the drive shaft then the impeller completely feathers itself andstops. If there is a load on the main drive shaft then the pitch settingof the blades will be one that balances, without causing rotation. Whenthe rollers are disengaged, the roller l6, its shaft 14 and the flexibleshaft l9 may be readily rotated by hand to actuate the traversing guidesand their associated elements.

While I have shown but one embodiment of my invention, it is susceptibleto modification without I do not wish, therefore, to be limited by thedisclosures set forth, but only by the scope of the appended claims.

-The invention described herein may be manufactured and used by or forthe Government of the United States of America for governmental purposeswithout the payment of any royalties thereon or therefor.

I claim:

1. A variable pitch impeller for driving the reel of a tow targetincluding, a rotatable shaft, a hub mounted on the shaft and having aplurality of radial sockets, a blade having its root rotatably.

mounted in each socket, a spur gear carried by the root of each blade,gear racks reciprocably mounted in the hub in meshing engagement withthe spur gear for adjusting the pitch of the blades, a member slidablymounted on said shaft and fixed against rotation relative thereto, themember having connection with the gear racks for reciprocating the same,a worm gear rotatably mounted on said shaft and having screw-threadedconnection with said member, a worm drive for imparting rotation to theworm gear so as to slide said member and actuate said gear racks, acontrol mechanism having a pair of spaced rotatable rollers, a flexibleshaft operatively connecting one of the rollers to said impeller shaft,the other roller being operatively connected to the worm drive, meansconnected to said latter roller permitting manual rotation of the sameso as to eifect adjustment of the blade pitch, an idler roller adaptedto be moved into engagement with said rollers whereby the rotation ofsaid impeller shaft is transmitted to said Worm drive, springpressedmeans supporting the idler roller out of engagement with said rollers,and cam means engageable with the spring-pressed means for moving saididler roller into engagement with said rollers.

2. A variable pitch impeller including, a rotatable shaft, a hub mountedon the shaft and having a plurality of radial sockets, a blade havingits root rotatably mounted in each socket, gear teeth carried by theroot of each blade, gear racks reciprocably mounted in the hub inmeshing engagement with the gear teeth for adjusting the pitch of theblades, a member slidably mounted on said shaft and fixed againstrotation, the mem- REFERENCES CITED The following references are ofrecord in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,670,099 DAsseler May 15, 19282,144,007 Austin Jan. 17, 1939 2,164,489 Berliner July 4, 1939 252,206,874 Briner July 9, 1940 2,316,538 Lea Apr. 13, 1943 2,368,761Hogan Feb. 6, 1945 FOREIGN PATENTS 39 Number Country Date 547,127 FranceSept. 13, 1922

